Embodiments of the present invention relate generally to a submersible pumping system and more particularly to a seal assembly in an electric submersible pumping system.
Typically, a submersible pumping system is widely used to obtain one or more fluids from subterranean reservoirs to the surface of the earth. In general, the submersible pumping system includes assemblies, such as a pump assembly, a seal assembly, and a motor assembly that are deployed into wells to recover the fluids from the subterranean reservoirs. Such assemblies include one or more components that are engineered to withstand an inhospitable downhole environment, such as wide ranges of temperature, pressure, and corrosive well fluids.
Furthermore, in submersible pumping systems with an electric drive, a dielectric fluid is employed within the motor assembly for insulation, lubrication and as a coolant. However, in certain environments, contaminated wellbore fluids may ingress into the motor fluid and may affect properties of the motor fluid. In one example, the properties of the motor fluid include favorable lubrication, dielectric strength, and chemical compatibility of the motor fluid.
In a conventional submersible pumping system, a motor protector is used to shield the motor from the wellbore fluids. Also, the motor protector is used to equalize pressure between the motor fluid and the wellbore fluids as well as to provide space for the motor fluid to expand and contract in response to thermal changes. However, under high temperature, parts of the motor protector may become permeable to water molecules in the wellbore fluids. The water molecules leak or diffuse from the wellbore fluids into the motor fluid, thereby degrading the dielectric strength of the motor fluid.